Massive Dilation of the Cystic Duct Stump With a Retained Stone Two Years After Complete Cholecystectomy Managed With Robotic-Assisted Resection.

Retained stones within the cystic duct stump are an uncommon but clinically important cause of postcholecystectomy syndrome. Dilation of the remnant duct secondary to an occluding stone is exceedingly rare, with only isolated reports of massive dilation in the literature. We describe a 67-year-old male (BMI 31.35) who presented two years after laparoscopic cholecystectomy with recurrent right upper quadrant biliary colic. Cross-sectional imaging demonstrated progressive enlargement of the cystic duct stump from mild dilation at 241 days to marked dilation of greater than 40 mm containing a 9 mm calculus by two years and 122 days. Magnetic resonance cholangiopancreatography was contraindicated because of unknown elbow orthopedic hardware. Endoscopic ultrasound confirmed the dilated cystic duct stump and occlusive stone; however, extraction was not possible because SpyGlass cholangioscopy was unavailable. The patient therefore elected for robotic-assisted resection using the da Vinci Xi platform. The dilated remnant containing the stone was excised using intraoperative near-infrared fluorescence imaging. Histopathology confirmed benign cystic duct tissue with a 9 mm calculus and no neoplasm. The patient experienced immediate symptom resolution, was discharged on postoperative day 2, and remained asymptomatic at follow-up. This case illustrates the mucopyocele-like pathophysiology of an obstructed cystic duct remnant. It highlights the diagnostic value of a failed therapeutic endoscopic retrograde cholangiopancreatography (ERCP) and endoscopic ultrasound, as well as the safety and precision of robotic resection when advanced endoscopic techniques are unavailable. Retained stones in the cystic duct stump can produce progressive, massive mucopyocele-like dilation years after laparoscopic cholecystectomy, closely mimicking recurrent biliary pathology. When advanced endoscopic techniques such as SpyGlass cholangioscopy are unavailable, a failed therapeutic ERCP and endoscopic ultrasound can still provide definitive diagnosis, while robotic-assisted resection offers safe, precise treatment with immediate and sustained symptom resolution. Greater recognition of this rare entity can prevent diagnostic delay and guide individualized management in similar atypical presentations of postcholecystectomy syndrome.